Build upon all your previous academic and extracurricular activities. Take the PSAT in October. Not only does it prepare you for and give you an insight into how you'll do on the SAT, but a high score will qualify you for a National Merit Scholarship. Now is also a good time to start preparing for SATs. Take SAT subject tests as you finish the relevant AP classes. Build relationships with teachers, coaches, employers, counselors or other relevant adults in your life who will be able to write college recommendations for you. In addition, inform them that you intend to ask them for recommendations at college application time.
In the summer following your junior year, try and take the SATs. This allows you more time to take them a second time early in your senior year, if you did not get the score you want. The summer before your senior year is also the time to make your list of colleges and take trips to look at colleges to which you will consider applying. Make sure you have your college list ready by the end of the summer before your senior year begins.
At the beginning of your senior year, take the SAT and any remaining subject tests early on. Gather your application materials according to school deadlines and start distributing requests for recommendation letters early enough to give your recommenders ample time to do the best job they can on your behalf.
Most competitive colleges and scholarship programs have early deadlines. If you plan on applying for early decision or early action, you will also have an early deadline. Make sure your materials are ready well in advance of the deadline to give you time to address any unforeseen problems. Most early deadlines are in November, and you should have decisions by the end of December. If you get into your school of choice, you are ready for college. Enjoy the rest of your senior year. If not, be ready for the next set of deadlines that run from January to March.
By April you should have heard from all the colleges to which you applied. Some responses will be big fat envelopes. If so congratulations! Other will be the small thin envelopes with one-page rejection letters. Hopefully, you will have a few colleges to choose from so you and your family can start making decisions about where you will go to college.
In summary, the key to a successful high school career that culminates in several college offers is dedication and advance preparation. Do not play things by ear or try to wing it. You need a good action plan, and that is where this a high school college prep timeline comes into play. Follow it, and you are bound to be successful.